ES2413807T3 - Method and apparatus for processing an audio signal - Google Patents

Abstract

Method for processing an audio signal, comprising: receiving a continuous stream of bits comprising an audio signal that includes a submix signal, an auxiliary signal and an extension signal, the submix signal being generated from the submix of a multi-channel audio signal, the auxiliary signal and the extension signal being intended to generate the multi-channel audio signal; acquiring (1420) length information of the extension signal: - reading the extension signal up to a first predetermined number of bits, and determining the length information value of the extension signal based on the number of bits read; - if the determined length information value is not equal to a first predetermined length value, acquiring the length information of the extension signal as a determined length information value; if not, reading the spread signal further up to a second predetermined number of bits, and determining the length information value of the spread signal based on the number of bits read so far; - if the determined length information value is not equal to a second predetermined length value, acquiring the length information from the extension signal as a determined length information value; otherwise, reading the extension signal further up to a third predetermined number of bits, determining the length information value of the extension signal based on the number of bits read so far, and acquiring the length information of the extension signal as information value of specified length; checking (1420) a level of the bit stream; determining (1430) whether or not decoding of the spread signal is to be omitted based on the level of the bit stream; if it is determined that decoding of the extension signal is to be omitted, omitting (1440) decoding (1450, 1460) of the extension signal based on the length information; and generating the multichannel audio signal by applying the auxiliary signal to the submix signal, wherein the auxiliary signal includes a spatial parameter for generating a multichannel audio signal, the spatial parameter including information representing an energy difference between channels, information A representing a correlation between channels and channel prediction coefficient information.

Description

Method and apparatus for processing an audio signal.

5 Technical field

The present invention relates to a method and an apparatus for processing an audio signal. Although the present invention is suitable for a wide variety of applications, it is particularly suitable for processing a residual signal.

Prior art

In general, an audio signal includes a submix signal and an auxiliary data signal. Additionally, the auxiliary data signal may include a spatial information signal and an extension signal. In this case, extension signal means an additional signal necessary to enable a signal to be reconstructed similarly to an original signal in the generation of a multichannel signal by upmixing the submix signal. For example, the extension signal may include a residual signal. Residual signal means a signal that corresponds to a difference between an original signal and an encoded signal. In multichannel audio coding, the residual signal is useful for the following cases. By

For example, the residual signal is useful for the compensation of an artistic submix signal or the compensation of specific channels in decoding. In addition, the residual signal is also useful for both compensations. Therefore, an introduced audio signal can be reconstructed into a signal more similar to an original signal using the residual signal to improve sound quality.

25 EP 1 315 148 deals with the MP3 PRO encoding format, in which extension data relating to bandwidth extension is provided, in an auxiliary data field containing length information.

EP 1 617 413 A2 refers to a method and apparatus for encoding / decoding multichannel audio data.

The document "The Reference Model Architecture for MPEG Spatial Audio Coding", by Herre J et al, discloses technologies for parametric coding of multichannel audio signals, in particular "spatial audio coding".

35 Similarly, the document “Der MPEG-2-Standard: Generische Codierung für Bewegtbilder und zugehörige Audio-Information. Audio-Codierung (Teil 4) “, Schröder E F et al, Fernseh- und Kino-Technik, vol. 48, No. 7-8, August 30, 1994, discloses the use of a continuous stream of extension bits, with information regarding its length, in the context of MPEG-2 audio coding.

Exhibition of the invention

Technical problem

However, if a decoder unconditionally decodes an extension signal, although, depending on the type of the decoder, the sound quality can be improved, the complexity increases and the operating load is increased.

On the other hand, since, in general, the header information for an audio signal is not variable, the

50 header information is inserted into a continuous stream of bits only once. However, in case the header information is inserted into the continuous bit stream only once, if it is necessary to decode an audio signal from a random timing point for a broadcast or VOD, it may not be possible to decode data frame information due to the absence of header information.

Technical solution

Accordingly, the present invention focuses on a method and apparatus for processing an audio signal, which substantially eliminates one or more of the problems due to the limitations and disadvantages of the technique.

60 related.

It is an object of the present invention to provide a method and apparatus for processing an audio signal according to claims 1 and 5, respectively.

Advantageous effects

The present invention provides the following effects or advantages.

First, in the case of decoding, the present invention selectively decodes an extension signal to enable more efficient decoding. In case of decoding on an extension signal, the present invention can improve the sound quality of an audio signal. In case of not decoding on an extension signal, the present invention can reduce complexity. On the other hand, even if decoding is performed on an extension signal, the present invention can improve sound quality by decoding only a predetermined low frequency part and can also reduce the operating load. In addition, in the case of using an audio signal for broadcasting or the like, the present invention can process an audio signal from a random timing point in such a way that a presence or non-presence of header information within the signal is identified. Audio.

Brief description of the drawings

The accompanying drawings, which are included to provide a more detailed understanding of the invention and are incorporated herein and constitute part thereof, illustrate embodiments of the invention and, together with the description, serve to explain the fundamentals of the invention.

In the drawings:

FIG. 1 is a block diagram of an audio signal coding apparatus and an audio signal decoding apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic block diagram of an extension signal decoding unit 90 according to an embodiment of the present invention;

FIG. 3 and FIG. 4 are diagrams to explain the fixed bit allocation of length information for an extension signal;

FIG. 5 and FIG. 6 are diagrams to explain the allocation of variable bits of length information for an extension signal depending on the type of length;

FIG. 7 and FIG. 8 are diagrams to explain the adaptive allocation of length information bits for an extension signal as a function of the actual length of the extension signal, in accordance with an embodiment of the present invention;

FIG. 9 is a diagram of a continuous bit stream structure that configures an audio signal with a submix signal, an auxiliary signal, and an extension signal, according to an embodiment of the present invention;

FIG. 10 is a diagram of a continuous bit stream structure that configures an audio signal with an auxiliary signal that includes an extension signal and a submix signal, according to an embodiment of the present invention;

FIG. 11 is a diagram of a continuous bit stream structure that configures an independent audio signal with a submix signal or an auxiliary signal, according to an embodiment of the present invention;

FIG. 12 is a diagram of a broadcasting streaming structure that configures an audio signal with a submix signal and an auxiliary signal;

FIG. 13 is a flow chart of a method of processing an extension signal that uses length information of the extension signal, in accordance with identification information indicating whether there is a header included in an auxiliary signal in case of using a signal audio for broadcasting or the like, in accordance with an embodiment of the present invention; Y

FIG. 14 is a flow chart of a method of decoding an extension signal selectively using length information of the extension signal according to a level of a continuous bit stream, according to an embodiment of the present invention.

Best way to practice the invention

In the description given below, additional features and advantages of the invention will be set forth, and they will be partially revealed from the description, or knowledge of them can be made.

by practicing the invention. The objectives and other advantages of the invention will be realized and achieved by means of the structure indicated particularly in the written description and in the claims thereof, as well as in the accompanying drawings.

To achieve these and other advantages, and in accordance with the purpose of the present invention, as it materializes and is widely described, a method for processing an audio signal in accordance with the present invention includes the steps of extracting an auxiliary signal. to generate the audio signal and an extension signal included in the auxiliary signal from a continuous stream of bits received, read length information of the extension signal, omit decoding of the extension signal or not use a result of decoding based on the length information, and generate the audio signal using the auxiliary signal.

To further achieve these and other advantages, a method for processing an audio signal includes the steps of acquiring synchronization information indicating a location of an auxiliary signal to generate the audio signal and a location of an extension signal included in the signal. auxiliary, skip the decoding of the extension signal or not using a decoding result based on the synchronization information, and generate the audio signal using the auxiliary signal.

To further achieve these and other advantages and in accordance with the purpose of the present invention, an apparatus for processing an audio signal includes a signal extraction unit that extracts an auxiliary signal to generate the audio signal and an included extension signal in the auxiliary signal from a continuous stream of received bits, an extension signal length reading unit that reads extension signal length information, a selective decoding unit that omits decoding of the extension signal or it does not use a decoding result based on the length information, and an upmix unit that generates the audio signal using the auxiliary signal.

To further achieve these and other advantages, an apparatus for processing an audio signal includes a synchronization information acquisition unit that acquires synchronization information indicating a location of an auxiliary signal to generate the audio signal and a location of a signal. extension included in the auxiliary signal, a selective decoding unit that omits decoding of the extension signal or does not use a decoding result based on synchronization information, and an upmixing unit that generates the signal from Audio using the auxiliary signal.

It will be understood that both the above general description and the following detailed description are exemplary and explanatory, and are intended to provide a further explanation of the invention as claimed.

How to practice the invention

Reference will now be made in detail to the preferred embodiments of the present invention, the examples of which are illustrated in the accompanying drawings.

FIG. 1 is a block diagram of an audio signal coding apparatus and an audio signal decoding apparatus according to an embodiment of the present invention.

Referring to FIG. 1, an encoding apparatus includes a submix unit 10, a submix signal coding unit 20, an auxiliary signal coding unit 30, an extension signal coding unit 40, and a multiplexing unit 50.

In the event that audio signals from multiple sources X1, X2, ..., Xn are input into the submix unit 10, the submix unit 10 generates a submix signal by submixing the audio signals from multiple sources. The submix signal includes a monophonic signal, a stereo signal, or an audio signal from multiple sources. The source includes a channel and, for convenience, is described as a channel. In the memory of the present invention, the explanation is made in reference to a monophonic or stereophonic submix signal. However, the present invention is not limited to the monophonic or stereophonic submix signal. The coding apparatus can use an artistic submix signal provided from the outside in a selective and direct manner. In the course of the submix, an auxiliary signal can be generated from a multichannel audio signal and an extension signal corresponding to additional information can also be generated. In this case, the auxiliary signal may include a spatial information signal and an extension signal. The submix, auxiliary and extension signals generated are encoded by means of the submix signal coding unit 20, the auxiliary signal coding unit 30, and the extension signal coding unit 40, and then transferred to the multiplexing unit 50, respectively.

In the present invention, "spatial information" means the information necessary for the coding apparatus to transfer a submix signal, generated from the multichannel signal submix, to the decoding apparatus, and necessary for the decoding apparatus to generate Multichannel signals by mixing up the submix signal. Spatial information includes spatial parameters. Spatial parameters include the CLD (channel level difference), which indicates an energy difference between

channels, the ICC (coherence between channels), which means a correlation between channels, the CPC (channel prediction coefficients), used in the generation of three channels from two channels, and so on. In addition, "extension signal" means additional information necessary to enable a signal to be reconstructed more similar to an original signal in the generation of multichannel signals by ascending mixing of the submix signal by the decoding apparatus. For example, additional information includes a residual signal, a residual artistic submix signal, a tree extension signal, artistic, and so on. In this case, the residual signal indicates a signal corresponding to a difference between an original signal and an encoded signal. In the following description, it is assumed that the residual signal includes a general residual signal or a residual artistic submix signal for the compensation of an artistic submix signal.

In the present invention, the submix signal coding unit 20 or the submix signal decoding unit 70 means a codec that encodes or decodes an audio signal not included with an auxiliary signal. Here, as an example of an audio signal not included with the auxiliary signal, a submix audio signal is taken. In addition, the submix signal coding unit 20 or the submix signal decoding unit 70 may include MP3, AC-3, DTS, or AAC. If a codec function is executed on an audio signal, the submix signal coding unit 20 and the submix signal decoding unit 70 may include a codec that is developed in the future, as well as a previously developed codec.

The multiplexing unit 50 can generate a continuous bit stream by multiplexing a submix signal, an auxiliary signal, and an extension signal, and then can transfer the continuous bit stream generated to the decoding apparatus. In this case, both the submix signal and the auxiliary signal can be transferred to the decoding apparatus in a continuous bit stream format. Alternatively, the auxiliary signal and the submix signal can be transferred, respectively, in independent formats of continuous stream of bits to the decoding apparatus. In FIGs. 9 to 11 details of continuous bit streams are explained.

In the case that previously transferred header information cannot be used because an audio signal is started to be decoded from a random timing point instead of being decoded from the beginning as a continuous stream of bits for broadcasting, it is possible to decode the audio signal using other header information inserted in the audio signal. In the event that the header information is lost in the course of the transfer of an audio signal, decoding should begin from any timing point of reception of a signal. Thus, header information can be inserted into an audio signal at least once. If header information appears in an earlier part of an audio signal only once, decoding cannot be performed due to the absence of header information in case of receiving an audio signal at a random timing point. In this case, header information can be included according to a preset format (for example, time interval, space interval, etc.). Identification information indicating a presence or non-presence of header information can be inserted in a continuous stream of bits. In addition, an audio signal can selectively include a header according to the identification information. For example, an auxiliary signal can selectively include a header according to the header identification information. In FIGs. 9 to 12 details of the structures of the continuous bit stream are explained.

The decoding apparatus includes a demultiplexing unit 60, a submix signal decoding unit 70, an auxiliary signal decoding unit 80, an extension signal decoding unit 90, and an upmixing unit 100.

The demultiplexing unit 60 receives a continuous stream of bits and then separates an encoded submix signal, an encoded auxiliary signal, and an encoded extension signal with respect to the continuous bit stream received. The submix signal decoding unit 70 decodes the coded submix signal. In addition, the auxiliary signal decoding unit 80 decodes the encoded auxiliary signal.

At the same time, the extension signal can be included in the auxiliary signal. It is necessary to efficiently decode the extension signal to efficiently generate multichannel audio signals. Therefore, the extension signal decoding unit 90 can selectively decode the encoded extension signal. In particular, the encoded extension signal can be decoded or decoding of the encoded extension signal can be omitted. Occasionally, if decoding of the extension signal is omitted, the encoded signal may be reconstructed to be more similar to an original signal and the encoding efficiency may be increased.

For example, if a level of the decoding apparatus is lower than that of a continuous stream of bits, the decoding apparatus cannot decode the received extension signal. Therefore, decoding of the extension signal can be omitted. Even if the decoding of the extension signal is available because the level of the decoding apparatus is higher than the continuous bit stream, the decoding of the extension signal can be omitted by other information obtained from the audio signal. . In this case, for example, the other information may include information indicating whether to perform decoding of the extension signal. This is explained in detail later in reference to FIG. 14.

In addition, for example, in order to skip the decoding of the extension signal, length information of the extension signal is read from the continuous bit stream and decoding of the extension signal can be omitted using the information of length. Alternatively, decoding of the extension signal can be omitted using synchronization information indicating a position of the extension signal. This is explained in detail later in reference to FIG. 2.

The length information of the extension signal can be defined in several ways. For example, fixed bits can be assigned, or variable bits can be assigned according to a predetermined length information type, or suitable bits can be adapted adaptively for a length of a real extension signal while reading the length of The extension signal. In FIG. 3 and FIG. 4, details of the fixed bit allocation are explained. In FIG. 5 and FIG. 6, details of the variable bit allocation are explained. In addition, in FIG. 7 and FIG. 8 details of adaptive bit allocation are explained.

The length information of the extension signal can be located within an auxiliary data area. In this case, the auxiliary data area indicates an area in which there is additional information necessary to reconstruct a submix signal into an original signal. For example, as an example of the auxiliary data, a spatial information signal or an extension signal can be taken. Therefore, the length information of the extension signal can be located within the auxiliary signal or an extension area of the auxiliary signal.

In particular, the extension signal length information is located within a header extension area of the auxiliary signal, a frame data extension area of the auxiliary signal, or both in the header extension area and in the area of frame data extension of the auxiliary signal. This is explained in detail later in reference to FIGs. 9 to 11.

FIG. 2 is a schematic block diagram of an extension signal decoding unit 90 according to an embodiment of the present invention.

Referring to FIG. 2, the extension signal decoding unit 90 includes an extension signal type information acquisition unit 91, an extension signal length reading unit 92, and a selective decoding unit 93. In addition, the unit Selective decoding 93 includes a level decision unit 94, an extension signal information acquisition unit 95, and an extension signal information omission unit 96. The extension signal decoder unit 90 receives a stream continuous bit for an extension signal of demultiplexing unit 60 and then outputs a decoded extension signal. Occasionally, the extension signal decoding unit 90 may not output an extension signal or may output an extension signal by completely filling with zeros a continuous stream of bits for the extension signal. In the case where an extension signal is not output, a method of omitting the decoding of the extension signal is useful. The extension signal type acquisition unit 91 acquires information indicating a type of an extension signal from a continuous stream of bits. For example, information indicating the type of the extension signal may include a residual signal, a residual artistic submix signal, a tree extension signal, artistic, or the like. In the present invention, residual signal is a generic expression of a general residual signal or a residual artistic submix signal for compensation of an artistic submix signal. The residual signal is useful for the compensation of an artistic submix signal in multichannel audio signals or for the compensation of specific channels in decoding. Optionally, both cases can also be used. If the type of the extension signal is decided by means of the extension signal type information, the extension signal length reading unit 92 reads a length of the extension signal decided by means of the type information of The extension signal. This can be achieved regardless of whether decoding of the extension signal is performed. Once the length of the extension signal has been read, the selective decoding unit 93 selectively performs decoding on the extension signal. This can be decided by the level decision unit 94. In particular, the level decision unit 94 selects whether to perform decoding of the extension signal by comparing a level of a continuous stream of bits with a level of a decoding apparatus. For example, if the level of the decoding apparatus is equal to or greater than that of the continuous bit stream, the decoding apparatus acquires information for the extension signal through the extension signal information acquisition unit 95 and then , decodes the information to output the extension signal. The extension signal that has been output is transferred to an uplink mixing unit 100 to be used in the reconstruction of an original signal or the generation of an audio signal. However, if the level of the decoding apparatus is lower than that of the continuous bit stream, decoding of the extension signal can be omitted by means of the extension signal information skip unit 96. In this case, it is possible skip the extension signal decoding based on the length information read by the extension signal length reading unit 92. In this way, in case the extension signal is used, reconstruction can be achieved in a manner that is closer to the original signal to improve sound quality. If necessary, the operating load of the decoding apparatus can be reduced by omitting the decoding of the extension signal.

As an example of the method of omitting the decoding of the extension signal in the omission unit of extension signal information 96, if the length information of the extension signal is used, length information can be inserted into the data of bits or bytes of the extension signal. In addition, the decoding can be kept running by omitting a bit field of the extension signal to a value obtained from the length information. They will be explained, referring to FIGs. 3 to 8, methods for defining the length information of the extension signal.

As another example of the method of omitting the decoding of the extension signal, decoding of the extension signal can be omitted based on synchronization information indicating a position of the extension signal. For example, you can insert a synchronization word that has predetermined bits at the point where the extension signal ends. The decoding apparatus continues searching in the bit field of the residual signal until it finds a synchronization word of the extension signal. Once the synchronization word has been found, the decoding apparatus stops the search process and then continues decoding. In particular, decoding of the extension signal can be omitted until the synchronization word of the extension signal is found. As another example of a decoding method according to the selection, in case the decoding of the extension signal is carried out, the decoding can be carried out after parsing the extension signal. When decoding of the extension signal is performed, the synchronization word of the extension signal is read but it may not be available.

FIG. 3 and FIG. 4 are diagrams to explain the fixed bit allocation of length information for an extension signal.

The length information of the extension signal can be defined by a bit or byte unit. If the length information is decided by the byte unit, this means that the extension signal is assigned bytes. FIG. 3 shows a method of defining length information for an extension signal in the simplest way. In addition, FIG. 4 shows the method shown in FIG. 3 schematically. A syntax element is defined to indicate the length information of the extension signal, and the syntax element is assigned default bits. For example, "bsResidualSignalLength" is defined as a syntax element and 16 bits are assigned as fixed bits. However, this method can consume a relatively considerable amount of bits. Therefore, the methods shown in FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are explained as follows.

FIG. 5 and FIG. 6 are diagrams to explain the allocation of variable bits of length information for an extension signal depending on the type of length.

FIG. 5 shows a method of defining one more syntax element, to define how many bits are used for "bsResidualSignalLength" in order to further reduce bit consumption. In addition, FIG. 6 schematically illustrates the method shown in FIG. 5. For example, “bsResidualSignalLengthtype” has just been defined as a type of length. If a value of “bsResidualSignalLengthtype” is zero, the “bsResidualSignalLength” is assigned four bits. If a value of “bsResidualSignalLengthtype” is 1, the “bsResidualSignalLength” is assigned eight bits. If a value of “bsResidualSignalLengthtype” is 2, the “bsResidualSignalLength” is assigned twelve bits. If a value of “bsResidualSignalLengthtype” is 3, the “bsResidualSignalLength” is assigned sixteen bits. In this case, the assigned bits are exemplary. Therefore, different bits can be assigned to the previously defined bits. To reduce bit consumption more than in the previous methods, the method shown in FIG. 7 and FIG. 8.

FIG. 7 and FIG. 8 are diagrams to explain an adaptive allocation of length information bits for an extension signal as a function of an actual length of the extension signal according to an embodiment of the present invention.

If an extension signal is entered, a length information value of the extension signal can be read up to a initially determined value. If the value of the length information is equal to a predetermined value, it can be read further to another determined value. If the value of the length information is equal to another predetermined value, it can be read further to another additional determined value. In this case, if the value of the length information is not another predetermined value, the corresponding value is output as the length information value, as it is at that time. Thus, the length information of the extension signal is read adaptively according to a real data length, whereby the bit consumption can be minimized. The example shown in FIG. 7 or FIG. 8.

In FIG. 7, as an example of the extension signal a residual signal is taken. If a residual signal is entered, four bits of the length of the residual signal are read. If a value of the length information (bsResidualSignalLength) is 24-1 (= 15), eight bits are additionally read as a value of bsResidualSignalLength1. If the value of the length information (bsResidualSignalLength) is (24-1) + (28-1) (= 15 + 255), twelve bits are additionally read as the value of bsResidualSignalLength2. In the same way, if the value of the information

of length (bsResidualSignalLength) is (24-1) + (28-1) + (212-1) (= 15 + 255 + 4,095), sixteen bits are additionally read as a value of bsResidualSignalLength3.

FIG. 8 schematically illustrates another example of the adaptive allocation of length information bits for an extension signal.

In FIG. 8, if an extension signal is input, four bits are preferably read. If a value resulting from reading length information is less than four bits, the corresponding value becomes the length information. However, if a value resulting from the reading of length information is greater than four bits, additionally eight bits are read. If the additionally read value is less than eight bits, a total value of read length information corresponds to 12 (= 4 + 8). However, if the value read additionally is greater than eight bits, again sixteen bits are read further. This is explained in detail as follows. First, if length information is entered, four bits are read. A real length information value is in a range of 0 ~ 14. If the length information value turns out to be 24-1 (= 15), the extension signal is also read further. In this case, the extension signal can be read further up to 28-2 (= 254). However, if the value of the length information corresponds to a value less than 24-1 (= 15), a value of the 0 ~ (24-2) (= 14) read is output, as it is at that moment. Once the value of the length information turns out to be (24-1) + (28-1), the extension signal is further read. In this case, the extension signal can be read further up to (216-1). However, if the value of the length information corresponds to a value less than 216-1, a value of the 0 ~ (216-1) (= 14) read is output, as it is at that time. In this case, as mentioned in the previous description, the assigned bits are exemplary in order to improve the explanation. Therefore, different bits can be assigned to the previously defined bits.

At the same time, the length information of the extension signal may be header length information of the extension signal or length information of the frame data of the extension signal. Therefore, the length information of the extension signal can be located in a header area and / or a frame data area. Referring to FIGs. 9 to 12 explain the structures of the continuous streams of bits for this.

FIG. 9 and FIG. 10 show embodiments of the present invention, in which a continuous bit stream structure is shown that configures an audio signal with a submix signal, an auxiliary signal, and an extension signal.

An audio signal includes a submix signal and an auxiliary signal. As an example of the auxiliary signal, a spatial information signal can be taken. Each of the submix signal and the auxiliary signal is transferred by means of a frame unit. The auxiliary signal may include header information and data information or may include only data information. Thus, in the general continuous stream file / structure that configures an audio signal, the header information precedes and follows the data information. For example, in the case of a general continuous stream file / structure that configures an audio signal with a submix signal and an auxiliary signal, such as header information, in a previous part, a submix signal header and a Auxiliary signal header. In addition, the submix signal data and the auxiliary signal data can configure a frame as data information behind the previous part. In this case, by defining an extension area of the auxiliary data, it is possible to locate an extension signal. The extension signal can be included within the auxiliary signal or it can be used as an independent signal. FIG. 9 shows a case in which the extension signal is used as an independent signal and FIG. 10 shows a case in which the extension signal is located in the extension area within the auxiliary signal. Therefore, if the extension signal exists, in the general continuous flow file / structure, in the previous part there may be, as header information, an extension signal header as well as the submix header and the header of spatial information. Behind the previous part, as data information, extension signal data as well as submix signal data and auxiliary signal data can be included to configure a frame. Since the extension signal can be selectively decoded, it can be located in a last part of the frame or can appear consecutively just behind the auxiliary signal. The length information explained in FIGs. 3 to 8 may appear within the header area of the extension signal and / or the data area of the extension signal. In this case, the length information that exists within the header area (extension signal header) indicates the length information of the extension signal header, and the length information that exists within the data area (signal data extension) indicates the length information of the extension signal data. Thus, the length information that exists in each of the areas is read from a continuous stream of bits and the decoding apparatus may omit decoding of the extension signal based on the length information.

FIG. 11 is a diagram of a continuous bit stream structure that configures an independent audio signal with a submix signal or an auxiliary signal according to an embodiment of the present invention.

An audio signal includes a submix signal and an auxiliary signal. As an example of the auxiliary signal, a spatial information signal can be taken. The submix signal and the auxiliary signal can be transferred respectively as independent signals. In this case, the submix signal has a structure such that a submix signal header (submix signal header �), such as header information, is located in an anterior part, and such that submix signal data (data of submix signal �, �, �, ... @), as data information, follow the submix signal header. Similarly, the auxiliary signal has a structure such that an auxiliary signal header (auxiliary signal header �), such as header information, is located in an anterior part, and such that auxiliary signal data (auxiliary signal data � , �, ..., @), as data information, follow the auxiliary signal header. Since the extension signal can be included within the auxiliary signal, a structure can be provided such that the extension signal follows the auxiliary signal data. Therefore, an extension signal header � follows the auxiliary signal header � and the extension signal data � follows the auxiliary signal data �. Similarly, the extension signal data � follows the auxiliary signal data �. In this case, in each of the extension signal header �, the extension signal data �, and / or the extension signal data �, ..., and @, signal length information of extension.

At the same time, unlike the general continuous stream file / structure, in case you cannot use previously transferred header information because an audio signal is decoded from a random timing point instead of being decoded from the beginning , the audio signal can be decoded using other header information included in the audio signal. In case of using an audio signal for broadcasting or the like, or of losing header information in the course of the transfer of an audio signal, the decoding should start from any moment of the reception of a signal. Therefore, the coding efficiency can be improved by defining identification information indicating whether the heading exists. It is explained as follows, referring to FIG. 12, a continuous flow structure for broadcasting.

FIG. 12 is a diagram of a broadcasting streaming structure that configures an audio signal with a submix signal and an auxiliary signal.

In the case of a continuous stream of broadcasting, if header information appears in an earlier part of an audio signal only once, decoding cannot be performed due to the absence of header information in case of receiving an audio signal in a random timing point. Therefore, the header information can be inserted into the audio signal at least once. In this case, the header information can be included according to a preset format (for example, time interval, spatial interval, etc.). In particular, the header information can be inserted in each frame, it can be periodically inserted in each frame with a fixed interval, or it can be inserted non-periodically in each frame with a random interval. Alternatively, the header information can be inserted once according to a fixed time interval (for example, 2 seconds).

A broadcast stream structure that configures an audio signal has a structure such that, between data information, header information is inserted at least once. For example, in the case of a broadcasting streaming structure that configures an audio signal, first a submix signal comes and the submix signal is followed by an auxiliary signal. In an earlier part of the auxiliary signal, synchronization information can be placed to differentiate between the submix signal and the auxiliary signal. In addition, identification information indicating whether there is header information for the auxiliary signal can be placed. For example, if the header identification information is 0, a successive read frame has only one data frame without header information. If the header identification information is 1, a successive read frame has both header information and a data frame. This is applicable to the auxiliary signal or to the extension signal. This header information may be the same as the header information that was initially transferred or may be variable. In case the header information is variable, new header information is decoded and then, according to the new decoded header information, data information transferred is decoded after the new header information. In case the header identification information is 0, a transferred frame has only one data frame without header information. In this case, to process the data frame, previously transferred header information can be used. For example, if the header identification information is 1 in FIG. 12, an auxiliary signal header � and an extension signal header � may appear. However, if a successive incoming frame has no header information since the header identification information was set to 0, extension signal header information may be used.

� previously transferred to process extension signal data �.

FIG. 13 is a flow chart of a method of processing an extension signal on the basis of length information of the extension signal according to identification information indicating whether there is a heading included within an auxiliary signal if used an audio signal for broadcasting or the like, according to an embodiment of the present invention.

Referring to FIG. 13, an auxiliary signal for the generation of an audio signal and an extension signal included in the auxiliary signal (1301) are extracted from a continuous stream of received bits. The extension signal can be included within the auxiliary signal. Identification information is extracted indicating if there is a header included in the auxiliary signal (1303). For example, if the header identification information is 1, this indicates that an auxiliary signal header is included in the auxiliary signal. If the header identification information is 0, this indicates that no auxiliary signal header is included in the auxiliary signal. In case the extension signal is included in the auxiliary signal, if the header identification information is 1, this indicates that an extension signal header is included in the extension signal. If the header identification information is 0, this indicates that no extension signal header is included in the extension signal. It is decided whether a header is included in the auxiliary signal according to the header identification information (1305). If the header is included in the auxiliary signal, length information (1307) is extracted from the header. In addition, decoding of the extension signal can be omitted based on the length information (1309). In this case, the heading plays a role in allowing the interpretation of each auxiliary signal and / or each extension signal. For example, the header information may include information for a residual signal, length information for a residual signal, synchronization information indicating a location of a residual signal, a sampling frequency, a frame length, the number of a band of parameters, tree information, quantization mode information, ICC (correlation between channels), parameter smoothing information, gain information for clipping prevention, information associated with a QMF (quadrature mirror filter), and so on. On the other hand, if the header is not included in the auxiliary signal in accordance with the header identification information, decoding of the extension signal may be omitted based on the length information previously extracted for the header (1311).

FIG. 14 is a flow chart of a method of decoding an extension signal selectively based on length information of the extension signal in accordance with an embodiment of the present invention.

A profile means that the technical elements for an algorithm in a coding process are standardized. In particular, the profile is a set of technical elements necessary to decode a continuous stream of bits and corresponds to a kind of sub-standard. A level defines a range of technical elements, which are prescribed in the profile, to be supported. In particular, the level plays a role in defining the capacity of a decoding apparatus and the complexity of a continuous stream of bits. In the present invention, the level information may include definitions for the profile and level. A method of decoding an extension signal can selectively vary according to the level information of the continuous bit stream and the level information of the decoding apparatus. For example, even if an extension signal appears in a transferred audio signal, decoding of the extension signal may or may not be performed as a result of the decision of the level information. On the other hand, even if decoding is performed, only a predetermined low frequency part can be used. In addition, decoding of the extension signal to the length information of the extension signal can be omitted in order not to execute decoding of the extension signal. Alternatively, even if the extension signal is read in its entirety, decoding cannot be executed. In addition, a portion of the extension signal is read, decoding can only be performed on the read portion, and decoding cannot be performed on the rest of the extension signal. Alternatively, the extension signal is read in its entirety, a portion of the extension signal can be decoded, and the rest of the extension signal cannot be decoded.

For example, in reference to FIG. 14, an auxiliary signal can be extracted from a continuous bit stream received to generate an audio signal and an extension signal included in the auxiliary signal (1410). In addition, information for the extension signal can be extracted. In this case, the information for the extension signal may include information of extension data type indicating a data type of the extension signal. For example, the information of the extension data type includes residual coding data, residual submix artistic coding data, artistic tree extension data, or the like. Therefore, the type of the extension signal is decided and length information of the extension signal can be read from an extension area of the audio signal (1420). Subsequently, a level of continuous bit stream is decided. This can be decided in reference to the following information. For example, if the type of the extension signal is the residual encoding data, the level information for the continuous bit stream may include the number of output channels, a sampling frequency, a bandwidth of a residual signal , and the like. Therefore, if the level information of the continuous bit stream explained above is entered, they are compared with level information so that a decoding apparatus decides whether the extension signal (1430) will be decoded. In this case, a level of the decoding apparatus can be set in advance. In general, the level of the decoding apparatus should be equal to or greater than a level of the audio signal. This is because the decoding apparatus should be able to decode the transferred audio signal in its entirety. However, in case a limitation is imposed on the decoding apparatus (for example, in case the level of the decoding apparatus is lower than that of the audio signal), decoding is occasionally possible. However, the corresponding quality may deteriorate. For example, if the level of the decoding apparatus is lower than that of the audio signal, it may not be possible for the decoding apparatus to decode the audio signal. However, in some cases, the audio signal can be decoded based on the level of the decoding apparatus.

If it is decided that the level of the decoding apparatus is lower than the continuous bit stream, it can be

5 skip the decoding of the extension signal based on the length information of the extension signal (1440). On the other hand, if the level of the decoding apparatus is equal to or greater than that of the continuous bit stream, the decoding of the extension signal (1460) can be performed. However, even if the decoding of the extension signal is executed, the decoding can only be performed on a predetermined low frequency portion of the extension signal (1450). For example, there is a case in which, since

10 that the decoding apparatus is a low power decoder, if the extension signal is completely decoded, efficiency is impaired, or since the decoding apparatus is unable to decode the full extension signal, a portion is useful Default low frequency extension signal. In addition, this is possible if the level of the continuous bit stream or the level of the decoding apparatus meets only a prescribed condition.

Industrial applicability

Therefore, in general there are several environments for encoding and decoding signals, and there may be several methods of signal processing according to the various conditions of the environments. At the moment

In the invention, an method of processing an audio signal is taken as an example, which does not limit the scope of the present invention. In this case, the signals include audio signals.

Although the present invention has been described and illustrated herein in reference to the preferred embodiments thereof, it will be apparent to those skilled in the art who are herein

25 various modifications and variations can be applied without departing from the scope of the invention. Thus, it is intended that the present invention encompass the modifications and variations of this invention that are within the scope of the appended claims.

Claims (4)

1. Method for processing an audio signal, comprising: 5 receiving a continuous stream of bits comprising an audio signal that includes a submix signal, an auxiliary signal and an extension signal, the submix signal being generated from the submixing of a multichannel audio signal, the signal being intended auxiliary and extension signal to generate multichannel audio signal; 10 acquire (1420) extension signal length information:

-

reading the extension signal to a first predetermined number of bits, and determining the length information value of the extension signal based on the number of bits read;

15 - if the determined length information value is not equal to a first predetermined length value, acquiring the length information of the extension signal as the determined length information value; if not, reading the extension signal additionally to a second predetermined number of bits, and determining the length information value of the extension signal based on the number of bits read so far; 20 - if the determined length information value is not equal to a second predetermined length value, acquiring the extension signal length information as a determined length information value; if not, reading the extension signal additionally to a third predetermined number of bits, determining the length information value of the extension signal based on the number of 25 bits read so far, and acquiring the extension signal length information as a given length information value; check (1420) a level of the continuous bit stream; 30 (1430) to determine whether or not to decode the extension signal based on the level of the continuous bit stream is to be omitted; if it is determined that decoding of the extension signal is to be omitted, 35 skip (1440) the decoding (1450, 1460) of the extension signal based on the length information; Y generate the multichannel audio signal by applying the auxiliary signal to the submix signal, 40 in which the auxiliary signal includes a spatial parameter to generate a multichannel audio signal, including the spatial parameter information representing a difference in energy between channels, information representing a correlation between channels and channel prediction coefficient information. Method according to claim 1, wherein the level of the continuous bit stream is checked (1430) using the number of an output channel of the audio signal, a sampling frequency, and information for a bandwidth of the extension signal.

3.

Method according to claim 1, wherein the extension signal includes a residual signal. fifty

4. The method according to claim 1, wherein in the omission stage, only a specific part of the extension signal is decoded with low frequency, based on a level of the decoder.

5.

Apparatus for processing an audio signal, the apparatus comprising means adapted to implement the method according to any of the preceding claims.